mc9s08ac128 Freescale Semiconductor, Inc, mc9s08ac128 Datasheet - Page 13

• Manufacturer Part Number: mc9s08ac128
• Description: 8-bit Hcs08 Central Processor Unit Cpu
• Manufacturer: Freescale Semiconductor, Inc

3.4
This section provides information about operating temperature range, power dissipation, and package thermal resistance. Power
dissipation on I/O pins is usually small compared to the power dissipation in on-chip logic and it is user-determined rather than
being controlled by the MCU design. In order to take P
actual pin voltage and V
(heavy loads), the difference between pin voltage and V
The average chip-junction temperature (T
where:
For most applications, P
is:
Solving equations 1 and 2 for K gives:
Freescale Semiconductor
Thermal Characteristics
T
θ
P
P
P
JA
1
2
3
4
A
D
int
I/O
Operating temperature range (packaged)
Maximum junction temperature
Thermal resistance
80-pin LQFP
64-pin QFP
44-pin LQFP
= Ambient temperature, °C
Junction temperature is a function of die size, on-chip power dissipation, package thermal
resistance, mounting site (board) temperature, ambient temperature, air flow, power dissipation
of other components on the board, and board thermal resistance.
Junction to Ambient Natural Convection
1s - Single Layer Board, one signal layer
2s2p - Four Layer Board, 2 signal and 2 power layers
= P
= Package thermal resistance, junction-to-ambient, °C/W
= I
= Power dissipation on input and output pins — user determined
int
DD
SS
I/O
+ P
× V
or V
<< P
I/O
DD
DD
int
and multiply by the pin current for each I/O pin. Except in cases of unusually high pin current
, Watts — chip internal power
and can be neglected. An approximate relationship between P
1,2,3,4
MC9S08AC128 MCU Series Data Sheet, Rev. 1
Rating
J
) in °C can be obtained from:
Table 3-3. Thermal Characteristics
P
T
D
Preliminary — Subject to Change
J
= K ÷ (T
= T
A
I/O
SS
+ (P
into account in power calculations, determine the difference between
or V
J
D
+ 273°C)
× θ
DD
JA
2s2p
2s2p
2s2p
will be very small.
Chapter 3 Electrical Characteristics and Timing Specifications
)
1s
1s
1s
Symbol
θ
T
T
JA
A
J
–40 to 125
T
Value
L
150
61
47
57
43
73
56
to T
D
H
and T
°C/W
Unit
J
°C
°C
(if P
I/O
is neglected)
Eqn. 3-1
Eqn. 3-2
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